The present invention relates to an apparatus for performing optical inspection tests on reagent strips having samples of body fluid thereon which reduces the likelihood of carryover of body fluid from one reagent strip to another.
Conventional spectrophotometers may be used to perform a number of different urinalysis tests utilizing a reagent strip on which a number of different reagent pads are disposed. Each reagent pad may be provided with a different reagent which causes a color change in response to the presence of a certain type of constituent in urine, such as leukocytes (white blood cells) or erythrocytes (red blood cells). The color change is detected by the spectrophotometer by illuminating the pad and taking a number of reflectance readings from the pad, each having a magnitude relating to a different wavelength of light. The color may then be determined based upon the relative magnitudes of red, green and blue reflectance signals, for example.
In a conventional spectrophotometer, the process of inspecting a reagent strip is performed by dipping the reagent strip in a urine sample, blotting excess urine from the reagent strip, placing the reagent strip at a designated location in the spectrophotometer, and pressing a start button which causes the spectrophotometer to begin automatic processing and inspection of the reagent strip.
FIG. 1A illustrates a prior art table 1 for supporting a reagent strip. The support table 1 has a receiving area 2 on which a reagent strip (not shown in FIG. 1A) is initially placed and an inspection area 3 to which the reagent strip is moved for optical inspection. Reagent strips are moved, one at a time, from the receiving area 2 to the inspection area 3 by a blotter arm 4, shown in FIG. 1B, which makes contact with each reagent strip.
The support table 1 has a plurality of upwardly extending ribs 5 designed to support the reagent strips so that they are held above the upper surfaces of the support table 1. The support table 1 has a first raised platform 6, having the approximate shape of a reagent strip, on which a reagent strip is positioned when being read by a first readhead (not shown), and a second raised platform 7 on which a reagent strip is positioned when being read by a second readhead (not shown).
The blotter arm 4 shown in FIG. 1B was designed to extract or remove urine from a reagent strip when it makes contact with the reagent strip so that significant amounts of urine from one reagent strip will not contaminate, or be left on, the portions of the support tray 1 with which subsequent reagent strips make contact. To that end, the surface of the blotter arm 4 which makes contact with reagent strips is provided with small capillaries (not shown) which draw urine away from the reagent strip due to capillary action.
Other prior art spectrophotometers have been designed to extract urine from reagent strips to prevent fluid carry over from one reagent strip to another. For example, in one prior art spectrophotometer, reagent strips were moved through the device on a paper web which is designed to absorb excess urine from each of the reagent strips.
Conventional reagent strips used in the spectrophotometer having the support table 1 shown in FIG. 1A have multiple reagent pads which are provided with reagents to test for various conditions. One such reagent pad is designed to detect "occult blood" in urine. Such a reagent pad is impregnated with a conventional reagent which causes a blue color to be formed in the presence of very small concentrations of blood in urine.